O-acyl decarbamoyl mitomycins

ABSTRACT

COMPOUNDS OF THE FORMULA 1,2-(-NH-),5,8-DI(O=),6-(H3C-),7-(H2N-),9-(R1-COO-CH2-), 9A-(CH3-O-)-2,3,5,8,9,9A-HEXAHYDRO-1H-PYRROLO(1,2-A) INDOLE AND A PROCESS FOR THEIR PREPARATION ARE PROVIDED WHEREIN R1 IS LOWER ALKYL OR SUBSTITUTED LOWER ALKYL. THESE COMPOUNDS ARE ANTIBIOTICS.

Kezoy Urzu, Kiirichi Nakano, and Toshinaka" Takahashi; l Tokyo-toJ-iiiam assigiwrs fof .'.Kyowa Hakkbf. K gyq Kabushik Kaisha,Tokyo-toJapa'nv v FiledJUIy-S,1969,`Ser.'Not839,923-

l '.Claimspriority, application' Japan, July-.23, 1968, u g t3/851,645.1?. wf. i Int.'Cl. C07d.27/54' U.S. Cl. 260-3276.3 l 7 Claims AiisTRAtrr oF 'rim DISCLOSURE Compounds of the formula and afprcessfor their preparation are provided wherein R1 islower alkylor-substituted lower alkyl. These compounds are antibiotics.

5.' uACKoRoU-ND youTHB:IriIFENTIOsI AND DESCRIPTION .oF THE PRIOR ART h siimmyfa 'etnie rqrmui is a known antibiotic and, additionally, nds use in treating tumors. This mitomycin, however, is strongly toxic and has undesirable side effects.

A process for preparing a derivative of the mitomycin of Formula I of the formular is disclosed in our copending application-Ser. No. 814,278, iiled Apr.' 8, n1 969.The compound Tof Formula II will #be referred to herein as'decarbamoyl'mitomycin C. As disclosed in our copending application Ser. 'No. 814,218) dearbainyl mitomycin C canfbefproduced by reacting the mitomycin of Formula1 anf'alkali' metalalcof' holate in an organic solvent. The alcoholate of a primary, secondary or tertiary alcohol may be employed as a nucleophilic reagent in an organic solvent (e.g., alcohol, terahydrofuran, dioxane, dimethyl formamide, benzene). The reaction is preferably carried'out at ambient temperature. Dry Ice' in excess of the quantity necessary to neutralize the solution is added,to they reaction mixture to neutralizeY excess alkali and the reaction mixture is then concenrtated in vacuo.vThel v'residue obtained after concentration is combined with acetone to extract the United States Patent "ice 3,641,053

" n i .-11 f f Patented',Feb.. 8,1972.

i I. Purid., for example, .fbY using Silica-gel chromatography to obtain decarbamoyl mitomycin C of Formu1a 1L A process is disclosed in our copending application Ser. No. 814,278 which may be used for preparing deriva- 5 tives of decarbamoyl mitomycin C of Formula II of th reaction product. The extract is concentrated and then n formula onioooR.

N-CORi wherein 'R1 is lower alkyl or substituted lower alkyl (e.g., halogen substituted lower alkyl). These acyl derivatives of decarbamoyl mitomycin C of Formula IH may be prepared by subjecting decarbamoyl mitomycin C of the Formula 1I to acylation to convert the CH2OH group at the 9position into a CHZOCORI group and to convert the hydrogen atom at the la-position into a lRlCO group wherein R1 is lower alkyl. Acylation is conducted by dissolving decarbamoyl mitomycin C of Formula II in a suitable solvent and adding an acid halide or acid anhydride or by condensing decanbamoyl mitomycin C of Formula II with lower carboxylic acid in the presence of a dehydrating condensing agent such as dicyclohexylcarbodiimide. Excess organic base is added to the reaction mixture for the purpose of preventing decomposition of the reaction product by acid which may be formed during the acylation reaction.

DESCRIPTION OF THE INVENTION An object of the present invention is the provision of derivatives of the compounds of Formula III which are effective antibiotics. A further object of the present invention s the provision of a process for preparing these derivatives of the compounds of Formula III.

According to the present invention, derivatives of the compounds of Formula I-II of the formula isy ylower alkyl or substituted lower alkyl (e.g., halogen substituted lower alkyl) in a weakly alkaline solution to deacylate the N-acyl group.

According to the present invention, thel diacylate of Formula III wherein R1 is lower alkyl or substituted lower alkylis dissolved in a water-miscible organic solvent (e.g.,`

ethanol, methanol, acetone, tetrahydrofuran, dimethylformamide) and is combined with a weakly alkaline solutiii (e.g., a solution" of sodium bicarbonate, sodium carbonate or ammonia). The mixture is allowed to stand at ambient temperature and, as a result, the N-acyl group is iirstjremoved followed bythe deacylation of the O-acyl group. The hydrolysis may proceed stepwise as shown in the following reaction sequence wherein R1 is lower alkyl or substituted lower alkyl. The reaction velocity may vary depending upon the properties of the starting materials, weakly alkaline solution, etc. used.

CHzOC CB1 loon.

(Stage III) In order to obtain the desired products with best yield, it is ladvantageous to discontinue the reaction at stage II by the proper selection of hydrolyzing agent and reaction time. For example, when the reaction is carried out at ambient temperature, best results can be obtained by carrying out the reaction in 10% NaHCO3 solution for 24 hours in the case where R1 is ClCHz.

The minimum concentration of representative O-monoacyl compounds of -Formula IV in I`,f/ml. of solution necessary to inhibit the growth of four representative types of pathogenic bacteria is shown in Table 1 as well as the 50 LD value for two of the three representative compounds.

As is apparent from the table, the compounds of the present invention have strong antibacterial activity and a low LD50 (mice, intravenous) so that the chemiccal therapeutical index is significantly improved. Moreover, the antitumor activity may be equal to or larger than that of the mitomycin of Formula I.

TABLE 1 R1=CH1C0 Cluco 01013100 60 Bacteria:

Bacillus subtilis (ATCC The following non-limitative examples illustrate the invention:

Example 1 Preparation of the compound of Formula IV wherein R1 is methyl (O-monoacetyl decarbamoyl mitomycin C): 75

One hundred milligrams of the compound of Formula III wherein R1 is methyl (diacetyl decarbamoyl mitomycin C) were dissolved in a small amount (about 2 ml.) of acetone and combined with 5 ml. of a 10% aqueous solution of NaHCO3. The mixture was allowed to stand at ambient temperature. The reaction mixture was extracted with ethyliacetate and the extract? was dehydratedwit'h anhydrous sodium sulfate. After filtration, the ltrate was concentrated yto dryness and subjected to column chromatography using 50 g. of silicagel. Developing and eluting with a solvent of chloroform-acetone( 1:1), a small amount of the unreacted starting material was rst eluted and O-monoacetyl decarbamoyl mitomycin C was then eluted. The main fraction was concentrated in vacuo to give 59.5 mg. of crystalline powder the infrared spectrum of which is shown in FIG. 1.

IExample 2 Preparation of the compound of Formula IV wherein R1 is ethyl (Omonopropionyl decarbamoyl mitomycin C):

The compound of Formula III wherein R1 is ethyl (decarbamoyl mitomycin C dipropionate) was treatedV 'in a similar manner to that described in IExample 1 to give O-monopropionyl decarbamoyl mitomycin C.

Example 3 Preparation of the compound of Formula IV wherein R1 is chloromethyl (O-monochloroacetyl decarbamoyl mitomycin C):

Three hundred (300) milligrams of the compound of Formula III wherein R is chloromethyl (dichloroaccztryl decarbamoyl mitomycin C) were combined with 5 rnl. of acetone and 15 ml. of 10% aqueous sodium bicarbonate solution. The mixture was allowed to stand for 24 hours at ambient temperature and was extracted with ethyl acetate. The extract was dehydrated with anhydrous sodium sulfate. After -filtering, the filtrate was concentrated in vacuo to dryness. Recrystallization from methanol yielded mg. of crystalline O-'monochloroacetyl decarbamoyl mitomycin C, the infra-red spectrum of which is show-n in FIG. 2.

We claim:

1. A compound of the formula CHZOC 0R; i 0GHz il N O l N-CORi wherein R1 is lower alkyl or halogen substituted lower References Cited alkyl is subjected to partial deacylation with a weakly UNITED STATES PATENTS alkaline solution selected from the group consisting of a sodium bicarbonate solution, a sodium carbonate solu- 3,429894 2/1969 Matsul et al' 260"3263 tion, or an ammonia solution. l

6. The process of claim 5 wherein the reaction is con- 5 NICHOLAS S' RIZZO Pnmary Exammer ducted in the presence of a Water-miscible organic solvent. J. A. NARCAVAGE, Assistant Examiner 7. The process of claim 6 wherein the water-miscible organic solvent is ethanol, methanol, acetone, tetrahydro- U S- Cl- X-R- furan or dimethylformamide. 10 26o-999 

